/Engine/Plugins/Runtime/NetworkPrediction/Source/NetworkPrediction/Public/NetworkPredictionProxy.h
The init function that you need to call. This is defined in NetworkPredictionProxyInit.h (which should only be included by your .cpp file)
template<typename ModelDef> void Init ( [UWorld](API\Runtime\Engine\Engine\UWorld) * World, const [FReplicationProxySet](API\Plugins\NetworkPrediction\FReplicationProxySet) & RepProxies, typename ModelDef::Simulation * Simulation, typename ModelDef::Driver * Driver )